Electrical control circuit for folding machines



Aug. 10, 1937., R CQNOVER 2,089,342

ELECTRICAL CONTROL CIRCUIT FOR FOLDING MACHINES Filed Sept. 19, 1956INVENTOR n9 RICHARD E. CONOVER 512% f/iqlay QWbyu ATTORNEYS PatentedAug. 10, 1937 UNITED STATES PATENT OFFICE ELECTRICAL CONTROL CIRCUIT FORFOLD- IN G MACHINES 11 Claims.

My invention relates to machines for folding articles, such as laundryfiatwork, and more particularly to an electrical control circuit forsupplying electrical energy for operating the folding mechanism of suchmachines at the proper time.

Folding machines, such as those designed for folding laundry fiatwork,have heretofore been equipped with elaborate and complex timing meansfor insuring that the folding blade will perform its function when thearticle has travelled to the proper position. In accordance with myinvention I have provided a folding mechanism, including an improvedelectrical control circuit, by means of which laundry flatwork, such assheets or other articles, may be accurately folded at the desired time.

It is therefore an object of my invention to provide an improvedelectrical control circuit for supplying current to operate the blade offolding machines by means of which articles, such as fiatwork, may befolded along the desired line.

Another object of my invention is to provide an electrical controlcircuit for folding machines in which the movementof the article to befolded through the machine varies the capacitance of the control circuitin such a manner that an electrical circuit is established at apredetermined time in response to the change in capacitance wh' chsupplies current to operate the folding blade.

A further object of my invention is to provide an improved electricalcontrol circuit for folding machines in which the movement of thearticle to be folded through the machine varies the capacitance of thecontrol circuit in such a manner that an electrical circuit isestablished to operate a folding blade in response to change incapacitance including means associated with the control circuit forvarying the time at which the blade operating circuit is established.

Another object of my invention is to provide an improved electricalcontrol circuit for folding machines, including two oscillating radio'frequency generators and means in response to the change of capacitancein the circuit during the movement of the article to ,be folded throughthe machine for establishing an'electrical circuit which suppliescurrent to operate the blade of the folding machine.

A still further object of my invention is to provide an improvedelectrical control circuit for folding machines, including two radiofrequency oscillators, the capacitances of which are varied by thepassage of the article to be folded through the machine in such a mannerthat an electrical circuit is established which operates the blade ofthe folding machine, including means for preventing the formation of acircuit for operating the folding blade when the capacitance in one ofsaid circuits is fixed,

My invention will be better understood by reference to the accompanyingdrawing, in which Fig. 1 is a diagrammatic view, partly in crosssection, of a folding machine, showing my improved electrical circuitand means controlled by the circuit for actuating the folding mechanism;and

Fig. 2 is a similar view of the machine, showing the folding mechanismin actuated position.

Referring to the drawing, the folding machine comprises a frame Isuitably mounted on legs or standards 2. Supported on frame I is adriver roll 3 and idler rolls 4, 5, 6 and l which support a conveyor orbelt 8. The roll 3 may be driven from any suitable source of power, suchas a motor, and the work is conveyed from left to right as illustratedin Fig. 1 of the drawing. Another belt or conveyor l I, supported bydriven roll 9 and an idler roll ID in line with conveyor 8 to receivework therefrom, is driven in synchronism with belt 8.

An article of fiatwork is thus conveyed along these belts and a foldingblade l2, mounted upon an arm l3 which is attached to a shaft [4, isactuated to thrust the article through a small gap between the conveyorsand from thence between roll l5 and conveyor 8. The roll [5 is rotatedin an opposite direction to roll 5 and the article in folded form dropsupon a conveyor l6 which is mounted upon a. driven roll I! and an idlerroll H3.

The blade I2 is actuated at the desired time by means of a controlcircuit including a source of direct current L1, L2, a radio frequencyoscillator 20, a low pass filter 22, a radio frequency oscillator 2|, anamplification system 23, a rectifier 24, and a grid glow or ignitioncontrolled discharge tube 25.

The radio frequency oscillator includes a tube 26 provided with an anode21, a grid 28 and a cathode 29. Current is supplied to the anode fromline L1 through conductors 30 and 3| and a radio frequency choke 32. Thecathode is connected to the negative terminal Le through conductors 33and 34. The plate 21 is also connected to one terminal of a fixedcondenser 35, the other terminal of condenser 35 being connected to aplate 31 by means of a conductor 38 which is supported above conveyorbelt I I. An additional plate 39 is fixed to the frame below the upperportion of conveyor belt II and conductor 40 electrically connected toplate 39 leads to the negative terminal L2. Plates 3! and 39 form acondenser 4 l, the capacitance of which is variable when the article tobe folded is drawn between the two plates upon conveyor belt H. Aninductance coil and a condenser 46 are connected in parallel fromconductor 33 to conductor 38 and current is supplied to grid 28 ofvacuum tube 26 throughinductance coil 41 and grid leak 48, a

grid condenser 49 being interposed between the terminals of the gridleak resistor 48.

The oscillating current generated by radio frequency oscillator 29 isconducted through the low pass filter 22 to vacuum tube 59 ofradiofrequency oscillator 2|. As illustrated, the low pass filter comprises aseries of induction'coils 52, 53, 54 and 55, a resistor 56 and aplurality of condensers 51, 58 and 59 which are connected acrossconductor and a conductor 69 leading to the negative terminal In atpoints between the respective inductance coils.

Radio frequency oscillator 2| includes a vacuum tube 59 which is ofthepentagrid converter type and includes an anode plate 65, grids 66 and61 which are connected together to form a screen grid, a detectorcontrol grid 68 which leads from low'pas's filter 22, a plate grid 69, acontrol grid 19 and a cathode 1|. Current is supplied to anode 85 fromthe line L1 through conductor 15,

intermediate. frequency transformer primary 16- and conductor 11. Screengrids and 61 are supplied from L1 through a resistor 19 the radiofrequency being bypassed by a condenser 82.

Current is supplied to the plate grid 69 from the positive terminalthrough conductors 15 and 83, resistor 84 and radio frequency choke 85and oscillator coil 86, the radio frequency component being bypassed bycondenser 88. The control grid 19 is biased through resistor 99, thebias being obtained from the voltage drop across resistor 93.

Condenser 94 bypasses resistor 93.

A fixed condenser 95 is connected to control grid 19 and the otherterminal leads through a conductor 96 to a plate 91 which is aflixed tothe frame of the machine above conveyor 8. An additional plate 98 isaffixed below the upper line of travel of conveyor Band is connected bymeans of a conductor 99 to'thenegative terminal L2. Plates 91 and 98provide a condenser I99, the

capacitance of which is variable when an article is passing uponconveyorv 8 between plates 91 and 98. Oneterminal of an inductance coilI95 is connected to condenser 95, the other terminal leading to thenegative terminal L2, and a variable condenser I96 is connected inparallel with coil cludes two amplification stages, each of which isprovided with a pentode tube.

Pentode tube III of the first amplification stage is provided withaplate I I2 which is supplied with current from line L1 throughconductors 39, 3| and H3, radio frequency choke II4, intermediatefrequency transformer primary I I5 and conductor H6. The cathode II 1 ofpentode III is connected to the negative terminal L2 through conductor 8and resistor H9.

Voltage is applied to control grid I 29 of pentode tube I from thesecondary coil I2I of the intermediate frequency transformer which has avariable condenser I22 connected across its terminals. Pentode tube IIIis alsoprovided with a screen grid I25, to which voltage is applied fromconductor I I3 through a resistor I26 and 'a conductor I21, and with asuppressor grid I28 I through conductor I29.

I and I63 to the negative terminal L2.

aosaaia to which voltage is appl ed from conductor H8 The amplifier isalso provided with the usual condensers I39 and I39a. Current fromcathode 1 passes through conductors I3| and I32 and condenser I33 tointermediate frequency transformer primary II5 connected in circuit witha variablecondenser I34. The intermediate frequency voltage passingthrough inductance coil II5is induced in secondary I49 of a secondamplification circuit including a pentode tube MI and an output coilI42. This circuit is similar to that just described.

The voltage from coil I42 is induced in coil I43 which is in circuitwith a variable condenser I44. One terminal of coil I43 is connected tothe plate I46 of rectifier 24 and the other terminal is connectedthrough resistor I41 to the cathode I48 of the rectifier. Rectifier 24is also provided with a control grid I49 which is connected to conductorI45. The cathode of rectifier 24 is terminal L2.

Voltage is applied to control grid I64 of ignition controlled dischargeor grid glow tube 25 by cury, neon or caesium. The grid glow tube isprovided with a plate I51 which. is connected to positive terminal L1 bymeans of conductors 39 and I59 and with a cathode |58a which isconnected by means of a conductor I59 to the switch I 69, the otherterminal of switch I 69 being electrically connected to the coil IGI ofa. solenoid, and conductors I62 and I63 to negative terminal In.Ignition controlled discharge tube 25 is of the type that requires apositive grid voltage to cause ignition.

In the operation of my improved circuit for controlling the foldingoperation, an oscillating current is generated by oscillator 29, thefrequency of which is controlled by the amount of inductance andcapacitance in the circuit including the capacitance of condenser 4|. Ina like manner the frequency of the oscillating current generated byoscillator 2| is controlled by the inductance and capacitance in thatcircuit, including the capacitance of condenser I99 which is formed byplates 91 and 98. As the article I19 to be folded is passed betweenplates 91 and 99, the capacitance of condenser I99 is increased whilethe capacitance of condenser 4| is fixed. As the article passes betweenplates 31 and 39, however, the capacitances of both condensers becomevariable. A frequency difference is then produced between oscillator 29and oscillator 2|.

When this frequency difference becomes the same as that to which theintermediate amplifier 23 is tuned, transmission occurs to the rectifiertube 24 the rectified voltage appearing across resistor I41.

A voltage is thus impressed upon control grid I64 which renders itpositive with respect to its cathode I58a. A circuit isaccordinglyestablished from line L1 through conductors I58 and I 59,switch I69, solenoid coil I6I and conductors I62 Folding blade I2 isnormally held in open position by means of a spring I68 which isattached to an arm I69 extending downwardly from arm I3. A

a rod I19 fixed to arm I69 has its free end extend-,

ing into the coil |6I and as coil |6| is energized the arm I19, whichconstitutes the armature of the solenoid, is drawn into the coil againstthe tension of spring I68 which actuates the blade connected throughresistor I41 to the negative I I2, thus folding the article and forcingit through the narrow gap between rolls 4 and I as illustrated moreparticularly in Fig. 2 of the drawing. As blade I2 is forced downwardlya boss "I on arm I69 is moved in contact with a tongue I'I2 projectinginwardly from switch I60. The other end of the switch is provided with arod I13 which extends through an opening in a bracket I14 afiixed to theframe of the machine. A spring I16 is interposed between switch I60 andbracket I14 which normally holds the switch in closed position. When theboss I'lI engages tongue I'I2, however, the switch is forced outwardlyagainst the compression of the spring and the switch is opened, therebybreaking the current flowing through ignition controlled discharge orgrid glow tube 25. Spring I68 then moves blade I2 to its normallyinoperative position as illustrated in Fig. 1 of the drawing.

Low pass filter 22 is provided to prevent the premature closing offolding blade I 2. It will be understood that the frequency appearing inthe plate circuit of the pentagrid converter may be a combination of thefundamental frequencies of oscillators 20 and 2I or be the combinationof any of the harmonics of the oscillating currents. If oscillator 20were connected directly to the mixer circuit of oscillator 2I it mightbe possible to produce a frequency to which the amplification system 23was tuned while the article is passing between plates 91 and 98 beforeits forward end reaches a position between plates 31 and 39 and blade I2would be prematurely actuated. In other words the second harmonic ofoscillator 2| might be combined with the fundamental of oscillator 20because with material passing between plates 91 and 98, oscillator 2Iwould generate the lower frequency. This combinaticn is particularly aptto happen when oscillator 20 is fixed and oscillator 2| is variable. Toprevent this the low pass filter 22 is inserted between oscillator 20and the mixing circuit of the pentagrid converter. The cutoff frequencyof this filter is such that no transmission can take place until afterthe material has entered between the plates 31 and 39. After this timeboth oscillators are continuously variable and the chances of other thanfundamental frequencies combining to produce the correct intermedi-- atefrequency is extremely remote.

The time at which blade I2 is actuated may be predetermined by means ofvariable condenser I06 of the oscillator circuit 2I. It will be notedthat condenser I06 of oscillator 2I is variable,

whereas condenser 46 of oscillator 20 is fixed and has a capacitancevalue which is normally higher than the capacitance of condenser I06when condenser I06 is adjusted to a low point setting. Condenser I06,however, has a capacitance value which is equal to condenser 46 whencondenser I06 is adjusted to its middle point setting and a lowercapacitance value than condenser 46 when condenser I06 is adjusted toits high point setting.

Assuming that it is desired to fold the article at a point one-third ofits length from its forward edge, condenser I06 is adjusted to a lowvalue capacitance setting so that when one-third of the article haspassed folding blade I2, the frequency of oscillator 20 will combinewith the frequency of oscillator 2| and a resulting intermediatefrequency will be produced which, when amplified, will cause a dischargeof the ignition controlled discharge tube 25 whereby blade I2 may beoperated. If it is-desired to fold the article along a line midwaybetween its ends, condenser I06 is adjusted to its middle point settingwhich increases the capacitance of oscillator 2I and the combinedfrequency produces an intermediate resulting frequency which operatesblade I2 when the middle portion of the article is below the blade. Tofold the article along a line which is one-third of the length from therear edge condenser I06 is adjusted to its high point setting and thefrequency of the two oscillators are not combined to produce theintermediate resulting frequency to which the amplification system istuned until two-thirds of the length of the article has passed underblade I2. It will therefore be seen that by simply adjusting condenserI06, the article may be folded along any desired line between its ends.

From the foregoing specification it will be apparent that I haveprovided an improved control circuit for folding machines by means ofwhich the article may be automatically folded at the desired time.

It will also be seen that by a simple adjustment of the variablecondenser in oscillator circuit 2| the line at which the fold occurs maybe predetermined so that the article may be folded along any desiredline.

It will also be apparent that by providing a low pass filter between thetwo oscillators the danger of premature folding of the article will beprevented.

To those skilled in the art many modifications of and widely differentembodiments and applications of my invention will suggest themselveswithout departing from the spirit and the scope thereof. My disclosureand the description herein are purely illustrative and are not intendedto be in any sense limiting.

What I claim is:

l. A folding machine comprising an article conveying means, articlefolding means, an electrical control circuit, means for varying theelectrostatic capacitance of said circuit when articles are conveyedthrough said machine, and means responsive to the variation of thecapacitance of the control circuit for actuating the folding means.

2. A folding machine comprising an article conveying means, articlefolding means, an electrical control circuit, including two condenserslocated at opposite sides of said folding means and being so arrangedthat the article to be folded passes between the plates of each of saidcondensers thereby varying the electrostatic capacitance of saidcondensers, and means responsive to the variation in the capacitance ofsaid condensers for actuating the folding means.

3. A folding machine comprising conveying means, article folding means,an electrical control circuit, including an ignition controlleddischarge tube having a plate, a grid and a cathode, means for supplyingcurrent to the plate of said tube, and two condensers located atopposite sides of said folding means and being so arranged that thearticle to be folded passes between the plates and varies thecapacitance of each condenser, means responsive to a predeterminedvariation in the capacity of said condensers for applying voltage to thegrid of said tube, whereby said tube is discharged, and means responsiveto the discharge of said tube for actuating said folding mechanism.

4. A folding machine comprising article conveying means, article foldingmeans, a control circuit including two radio frequency oscillators,

the capacity of one of which is varied by the movement of an article tothe folding means and the capacity of the other of which is varied asthe article passes beyond the folding means, an ignition controlleddischarge tube having an anode plate, a grid and a cathode, means for Vsupplying current to the plate of said tube, means responsive to thechange in capacity of the radio frequency oscillators for applyingvoltage to the grid of said tube, thereby causing a discharge of saidtube, and means responsive to the dis-' charge of said tube foroperating the folding mechanism.

5. A folding machine comprising article concontrolled discharge tubehaving an anode plate,

a cathode and a grid, means for applying the combined voltages generatedby said oscillators to the grid of said tube, whereby discharge of saidtube occurs, and means responsive to the discharge of said tube foroperating the folding mechanism.

6. A folding machine comprising article conveying means, an articlefolding means, a control circuit including an ignition controlleddischarge tube having a plate, a grid and a cathode, means for supplyingcurrent to the plate of said tube, two radio frequency oscillators, thecapacity of one of which is varied as the end of the article movestoward the folding means and the capacity of the other of which variesas the forward end of the article moves beyond the folding means, meansfor combining the voltages generated by said oscillators, means foramplifying the voltage and applying the amplified voltage to the grid ofsaid discharge tube, and means responsive to the discharge of, said'tube for operating the folding means.

7. A folding machine comprising an article conveying means, articlefolding means, a control circuit including an ignition controlleddischarge tube having a plate, a grid and a cathode, two radio frequencyoscillators, the capacity of one of which is varied by the movement ofthe forward end of the article to the folding means and the capacity ofthe other of which is varied by the movement of the article beyond thefolding means, means for combining the oscillating voltages generated bysaid oscillators at a predetermined time after the forward end of thearticle has been moved past the folding means, means for amplifying thevoltage and applying the amplified voltage to the grid of said dischargetube, and means responsive to the discharge of said tube for operatingthe folding mechanism. 8. A folding machine comprising article conveyingmeans, article folding means, a control circuit including an ignitioncontrolled discharge tube having a plate, a grid and a cathode, tworadio frequency oscillators, one of -whlch has an adjustable capacitanceand a capacitance which varies as the article moves towards the foldingmechanism and the other of which has a fixed capacitance and acapacitance which varies as the article moves beyond the folding means,said radio frequency oscillators being connected together and one ofsaid oscillators being provided with means for combining the oscillatingvoltages of both oscillators and converting the combined voltage into avoltage having intermediate frequency oscillations, means for applyingcurrent to the plate of said discharge tube, means for amplifying theconverted oscillating voltage and applying it to the grid-of thedischarge tube,

thereby causing a discharge of said tube, and means responsive to thedischarge of said tube for actuating the folding mechanism.

' 9. A folding machine comprising an article conveying means, articlefolding means, an ignition controlled discharge tube having a plate, agrid and a cathode, two radio frequency oscillators, means responsive tothe movement of the article upon said conveying means for varying thecapacity of both of said oscillators, an ad- L justable condenserassociated with one of said a oscillators, and a fixed condenserassociated with the other oscillator, means for connecting said,

oscillators together, means associated with one of said oscillators forcombining the oscillating voltages generated by both oscillators andconverting them into an intermediate frequency voltage, means foramplifying said voltage, and means foiapplying the amplified voltage tothe grid of said discharge tube, thereby causing a discharge of saidtube, and means responsive to the discharge of said tube for actuatingthe folding means, the time at which the folding means is actuated beingdetermined by the relative capacitance of the two oscillators.

10. A folding machine comprising an article conveying means, articlefolding means, a control circuit including an ignition controlleddischarge tube having a plate, a grid and a cathode,

means for applying current to the plate of said discharge tube, tworadio frequency oscillators, the capacity of each of which is varied byan article being conveyed through the machine, a low pass filterconnecting the two oscillators, one of said oscillators being capable ofgenerating an oscillating voltage and combining it with the voltage ofthe other oscillator to produce an intermediate frequency voltage, meansfor amplifying the intermediate frequency voltage, means for applyingthe amplified voltage to the grid of said dischargetube whereby saidtube is discharged, and means responsive to the discharge of said tubefor actuating the folding mechanism.

11. A folding mechanism comprising an article conveying means, articlefolding means, a control circuit including an ignition controlleddischarge tube having a plate, a grid and a cathode, means for supplyingcurrent to said plate, two radio frequency oscillating circuits, one ofsaid oscillating circuits including a pentagrid convertor and anadjustable condenser and the other circuit including a fixed condenser,means for varying the capacity of both oscillating cir- Jill RICHARD E.CONOVER.

